1. Field of the Invention
The present invention relates generally to actuators, and more particularly, to actuators capable of generating high pressure at a high operating frequency.
2. Prior Art
Commercial valves for high pressure and high flow rate are typically very large and have a low operating frequency (cycle). On the contrary, valves having fast operating frequencies are known in the art for low pressure and low flow rates. Such valves are typically very small in size (e.g., MEMS actuators). Presently, electromagnetic valves can meet some high pressure/flow specification and can also have relatively fast operating frequencies if complex techniques are employed. However, such techniques come at the expense of size and power. Therefore, electromagnetic valves are very bulky and expensive.
Therefore, there is a need in the art for a valve actuator which operates at high pressure and flow as well as a fast operating frequency that is less bulky and expensive than the valve actuators of the prior art.
Therefore it is an object of the present invention to provide an actuator that is capable of use on high pressure and high flow valves that is less bulky than similar use valve actuators of the prior art.
It is another object of the present invention to provide an actuator that is capable of use on high pressure and high flow valves that is less expensive than similar use valve actuators of the prior art.
It is still a further object of the present invention to provide an inexpensive and small actuator that can apply a relatively large force through a relatively large displacement.
Accordingly, an actuator for applying an actuating force through a total displacement is provided. The actuator comprises: an actuator body; n piezo members supported by the body where n is an integer greater than or equal to two, each of the piezo members generating a force and a displacement upon application of a voltage thereon; and nxe2x88x921 levers rotatably disposed in the body and each having first and second ends corresponding to two of the n piezo members such that the displacements of the n piezo members are accumulated to generate the total displacement at the nth piezo member.
Preferably, at least one of the n piezo members comprises a plurality of sheet elements of a piezo material stacked upon each other to form a piezo stack. Alternatively, at least one of the n piezo members is a solid bar of a piezo material.
The actuator preferably further comprises a rotatable joint between each of the first and second ends of at least one of the nxe2x88x921 levers and a portion of each corresponding piezo member. Each rotatable joint preferably comprises: the piezo member corresponding to the at least one lever having an end portion; a cap plate disposed on the end portion, the cap plate having a concavity formed thereon; the lever having a concavity formed on one of the first and second ends corresponding to the piezo member; and a ball disposed in the concavities of the cap plate and lever for providing a relative rotation therebetween.
The body preferably comprises first and second end plates having a pair of aligned bores corresponding to each of the nxe2x88x921 levers, each of the nxe2x88x921 levers having a shaft rotatably disposed in the pair of aligned bores.
Preferably, at least one of the nxe2x88x921 levers are rotatably disposed in the body such that the displacement from one of the n piezo members acting on the first end of the at least one of the nxe2x88x921 levers is amplified at the second end of the at least one of the nxe2x88x921 levers.
Each of the piezo members preferably have corresponding first and second ends and the nxe2x88x921 levers are disposed in an alternating manner at the first and second ends between adjacent piezo members.
More specifically, an actuator for applying an actuating force through a total displacement is provided where the actuator comprises: an actuator body; a first piezo member having a first end fixed to the body and a second free end, the first piezo member generating a first force and a first displacement upon application of a first voltage thereon; a second piezo member supported in the body and having first and second free ends, the second piezo member generating a second force and a second displacement upon application of a second voltage thereon; and a first lever rotatably disposed in the body and having a first end corresponding to the second free end of the first piezo member and a second end corresponding to the second free end of the second piezo member such that the first and second displacements of the first and second piezo members are accumulated to generate the total displacement at the first free end of the second piezo member.
The actuator preferably further comprises: a third piezo member supported in the body and having first and second free ends, the third piezo member generating a third force and a third displacement upon application of a third voltage thereon; and a second lever rotatably disposed in the body and having a first end corresponding to the first free end of the second piezo member and a second end corresponding to the first free end of the third piezo member such that the first, second and third displacements of the first, second and third piezo members are accumulated to generate the total displacement at the second free end of the third piezo member.
Preferably, the first lever is rotatably disposed in the body such that the displacement from the first piezo member acting on the first end of the first lever is amplified at the second end of the first lever and/or the second lever is rotatably disposed in the body such that the displacement from the second piezo member acting on the first end of the second lever is amplified at the second end of the second lever.
At least one of the first and second piezo members preferably comprises a plurality of sheet elements of a piezo material stacked upon each other to form a piezo stack. Alternatively, at least one of the first and second piezo members is a solid bar of a piezo material.
The actuator preferably further comprises a rotatable joint between the first end of the first lever and the second free end of the first piezo member and between the second end of the first lever and the second free end of the second piezo member. Preferably, each of the rotatable joints comprises: a first cap plate disposed on the second fee end of the first piezo member and a second cap plate disposed on the second free end of the second piezo member, the first and second cap plates having a concavity formed thereon; the first and second ends of the first lever having a concavity formed thereon and corresponding to the concavity on the first and second cap plates; and a first ball disposed in the concavities of the first cap plate and the first end of the first lever and a second ball disposed in the concavities of the second cap plate and second end of the first lever.
Preferably, the body comprises first and second end plates having a pair of aligned bores, the first lever having a shaft rotatably disposed in the pair of aligned bores.
Still further provided is a method for actuating a force through a total displacement. The method comprising: providing two or more piezo members supported in a body, each of the two or more piezo members generating a force and a displacement upon application of a voltage thereon; and accumulating the displacements of the two or more piezo members to generate the total displacement.
The method preferably further comprises amplifying at least one of the displacements from the two or more piezo members.